1982

6.0

1994

5.8

1999

7.5

2001

6.1

2001

3.5

1991

5.9

1990

6.7

1992

6.9

1998

6.4

1997

7.5

2006

5.2

2007

4.7

1985

6.0

1979

6.1

1980

5.5

2007

5.9

1968

5.1

1970

4.8

1981

5.0

1996

2.2